Device for the synchronization of alternating-current machines



May 1, 1928.

R. MICHL DEVICE FOR THE SYNCHRONIZATION OF ALTERNATING CURRENT MACHINES Filed Jan. 10. 1924 3 Sheets-Sheet 1 May 1, 1928.

R. MICHL DEVICE FORTHE SYNCHRONIZATION OF ALTERNATING CURRENT MACHINES Filed Jan. 10. 1924 3 Sheets-Sheet 2 May 1, 1928. 1,667,794

R. MICHL DEVICE FOR THE SYNCHRONIZATION OF ALTERNATING CURRENT MACHINES Filed Jan. 10, 1924 5 Sheets-Sheet 5 Patented May 1, 1928.

UNITED STATES 1,667,794 PATENT OFFICE.

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Application filed January 10, 1824, Serial No. 685,489, and in Germany January 12, 1928.

As is well known, small electric alternating current synchronous motors can be synchronized by simply causing them by hand to run, when excited by the working current,

I at as nearly synchronous a speed of revolution as possible, until sync roni sm is obtained, that is, the motor has gt 1nto phase with the working current. This method, however, is inconvenient and uncertain, as usually the attempt must be repeated a number of times before it is successful. What 18 required therefore is an arrangement, by which synchronism may be obtained at once with certainty both by hand and automatil6 cally. Such an arrangement forms the subject of the present invention. It is characterized by the feature that for the synchronization of and the prevention of hunting in single phase and polyphase alternating ourrent synchronous machines, the rotor 1s given a moment of inertia, which increases and decreases with the speed of revolution of the same.

For this purpose centrifugal weights or 2 pendulums may for instance be used, such as are commonly used in speed governors. These weights or pendulums, referred to below as synchronizing pendulums, may also be used for other purposes, for instancefor automatic starting, for operating the switch of the starting motor and the like.

The accompanying drawings show a number of examples of how the invention may be applied and further modifications, the magnetic part of the synchronous machine being omitted, as applied to small synchronous motors, which may be used forthe electric operation of clockwork mechanisms and the like, Figures 1 and 2, 3 and 4, 7 and 8 being three examples, in which the starting of the synchronous motor is eifecte'd by hand, While Figs. 5 and 6 show an example, 1n which the synchronizing pendulums for selfstarting operate the starting switch andat the same time a clockwork mechanism. Flgs. 9 and 10 show a further modification of the starting electromagnet.

The synchronizing pendulums a 1n .Figs. 1 and 5 swing under the influence of centrifugal force about the pins 1) in a plane passing through the axis of rotation of the rotor 0" having the usual fieldco1l w. The sameapplies to the pendulums a of Figs.

3 and 4, but in this case the weights have not the form of balls as in Figs. 1 and 5, but, for economizing space, are made in the form of segments of a circular disc, which for the same reason move without a shaft on sliding surfaces at right angles to the axis and are not ke t in a state of equilibrium with the centrifugal force as in Figs. 1 and 5 by their own weight, but by spring action.

In the example shown in Figs. 7 and 8 the synchronizing pendulums a are shown in Fig. 8 from below and are mounted on the under surface of the disc-shaped rotor '0 of the synchronous motor, so as to rotate about the pins or bolts 0!. Owing to this arrangement the pendulums move under the action of the forces in a plane at right angles to the axis of rotation. By this arrangement, not only the centrifugal forces due to the rotation, but the forces resulting from the movement and inertia of the synchronizing pendulums a act in the same direction as the centrifugal forces, which latter forces are thereby magnified.

If the rotor of a single or polyphase synchronous motor or generator be provided with the synchronizing pendulums a, a and a shown in Figs. 1, 3, 4, 5, 7 and 8, according to one of the arrangements referred to, it is sufiicient to bring it, when excited, either by hand or by motive power, to a speed of revolution, which is not less than the synchronous speed. The getting into phase is effected automatically by the action of the synchronizing pendulums, while at the same time the pendulums prevent hunting and .1 getting out of phase. In the case of small synchronous motors, such as are for instance used for driving clockwork mechanisms, the motor may be started readily by hand by means of the devices shown in Figs. 1, 2 and 7 and in the case of Figs. 1 and 2 by the pawl e, together with the corresponding inertia and centrifugal pendulum 7, which are mounted with the cam swell h on the sleeve g, being pressed by the second cam swell k by means of the milled head 2', until the two cam swells cease to engage owing to their rotary motion, and the sleeve 9 together with the pawl e and the pendulum f is caused to spring back through the action dulums a being caused to rotate. The pawl e is caused to disengage from the ratchet wheel by the inertia of the pendulum f at the moment, in which the cam swell It strikes against the stop m, on the spring contracting again. In the hand-starting device shown in Fig. 7 the rotation of the milled head a" by handis transmitted through the two toothed wheels 11. and n directly by way of the pawl e and the pendulum f, which is not shown, to the rotor c.

For the self-starting of a synchronous motor the synchronizing pendulums a may hands, when the drive of the clock is tem-- porarily interrupted. In the diagram of connections according to Fig. 5, w and w are the terminals of the drivin alternating current connected with the win ing a: of the synchronous motor, by conductors 20 and 21 and fuses y and y. The electromagnetic starting device may in this case consist, as is shown for instance in Figs. 5 and 6, of an elect-romagnet g the coils of which are connected in series and also on the one hand with the fuse 3 by conductor 22 and on the other hand with a stationary contact 23 by a conductor 24. A relatively movable contact 25 is attached to the lever p and is connected with the terminal of the fuse y by a conductor 26. The armature r of the electromagnet transmits its attractive force through the lever ,9, the pawl e and the pendulum f, already described in connection with the hand starting device, and the ratchet wheel Z to the rotor c. For putting the synchronous motor into operation, a single movement of the armature r will usually be found to be sufiicient, but this movement can be converted into a periodically oscillating one, by the provision of a contact-making device operated by the said armature, which breaks the circuit, when the armature is attracted and closes the circuit again when it swings back, whichoscillating movement lasts as long as the circuit is" closed by the contact lever 77,

In the example shown in Figs. 9 and 10 of the electromagnetic starting device, the pawl e and the pendulum 7", which controls the pawl directly, for instance by its enertia, are mounted on a two-armed armature a, which is mounted symmetrically on the shaft t, by which means, not only the mechanical transmission resistances between the electromagnet armature and the pawl e are overcome,

but, owing tothe short path of the magnetic lines of force between the two poles u and u of the electromagnet 20 through the armature 7- the ma netic stray field becomes very small an consequently the action of the magnet becomes very strong.

The synchronizing pendulums described above can also be used for preventing hunting and a getting out of phase in the case of larger synchronous generators and motors as well, in which the synchronization 1s to be effected with the means ordinarily employed for this purpose, such as phase volt meters, phase lamps and the like.

What I claim is 1. In combination, an alternating current synchronous machine including a rotor and a separate automatically varying synchronizing centrifugal pendulum adapted to impart to the rotor an additional variable inertia moment increasing and decreasing with the speed of revolution of the rotor.

2. In combination, an alternating current synchronous machine including a rotor, a separate synchronizing centrifugal pendulum adapted to impart to the rotor an additional variable inertia moment increasing and decreasing with the speed of revolution of the rotor, and starting means, adapted to impart to the rotor and to the centrifugal pendulum an impulse not less than=the synchronous speed of the motor.-

. 3. In combination, an alternating current synchronous machine includin a rotor a separate synchronizing centri gal pendulum adapted to impart to the rotor an additional variable inertia moment increasing and decreasing with the speed of revolution of the rotor, starting means adapted to impart to the rotor and to the centrifugal pendulum an impulse not less than the synchronous speed of the motor, a pawl and ratchet wheel mechanism inserted between thesaid starting means at the one side and the rotor and the synchronizing pendulum at the other side, means for throwing the pawl and ratchet mechanism into or out of enga 'ement.

' 4. In combination, an alternating current synchronous machine, including a rotor and means for transmitting the rotation of the rotor to a clockwork-mechanism, a separate synchronizing centrifugal pendulum adaptma netic starting means and the said secon ary driving means, in such a way, that an undue slackening speed of the synchronizing pendulum sets the secondary driving means free for action on the clockwork mechanism and closes the circuit of the electromagnetic starting means, whilst the normal speed of the synchronizing pendulum arrests the said secondary driving means.

5. In combination an alternating current synchronous machine, means by which an inertia moment is imparted to the rotor of the machine, which inertia moment increases and decreases with the speed of revolution of the rotor, said means consisting of centrifugal and inertia pendulums, auxiliary fiy-weights, a pawl and ratchet mechanism and means connecting the latter with the said auxiliary fly-weights whereby the pawl is automatically caused by inertia to engage with the ratchet, on the auxiliary force coming into operation and to be automatically re eased by the inertia, after the said auxiliary force has ceased to act, as set forth.

6. In combination a small synchronous.

motor, means by which an inertia moment is imparted to the rotor of the machine, which inertia moment increases and decreases with the speed of revolution of the rotor, said means consisting of centrifugal and inertia pendulum s, auxiliary flyweights, a pawl and ratchet mechanism means connecting the latter with the said auxiliary fly-weights in such a manner that the pawl is automatically caused by inertia to engage with the ratchet, on the auxiliary force coming into operation and to be automatically released by the inertia after the said auxiliary force has ceased to act and electromagnetic means for facilitating the starting up of the motor, as set forth.

7. The combination as claimed in claim 6, characterized in that the electromagnetic means includes an electromagnet and a pivoted armature, the pawl of the pawl and ratchet mechanism being mounted directly on the said armature, as set forth.

In testimony whereof I have signed my name to this specification.

ROBERT MICHL. 

